Forensic Dentistry and Bite Marks

30.04.2011

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Forensic Dentistry and Microbial Analysis of Bite Marks
By Darnell Kennedy
APJ Issue - March 2011: pp. 6 - 15.

The below are selected highlights from a fascinating article on forensic dentistry. For the full article, click on the subscribe button.

Humans have used their teeth as both tools and weapons since the dawn of time. Bite marks may be inflicted during violent altercations in both offensive and defensive combat. These marks can be used forensically for law enforcement purposes.

The field of forensic dentistry is “that area of dentistry concerned with the correct management, examination, evaluation and presentation of dental evidence in criminal or civil legal proceedings.”(1)  The field consists of two primary areas. The first is disaster victim identification or identification of people who have become casualties as a result of a crime. The second is the identification, examination and evaluation of bite marks which occur during sexual assaults and child abuse.(2)

A bite mark may be defined as having occurred as a result of either a physical alteration in a medium caused by the contact of the teeth, or a representative pattern left in an object or tissue by the dental structures of an animal or human.(3) A prototypical human bite mark is described as being a circular or oval patterned injury consisting of two opposing symmetrical, U-shaped arches separated at their bases by open spaces. Along the periphery of the arches can be a series of abrasions, contusions and/or lacerations indicative of the size, shape, arrangement and distribution of the contacting surfaces of the biting dentition.(3)

Historical Bite Mark Cases

Salem Witch Trials

The first reported incident of bite mark identification occurred in 1692 in what is now commonly referred to as the Salem Witch Trials. Reverend George Burroughs was accused of soliciting young women into witchcraft by pinching, choking and biting his victims. It was reported that during the trial Burroughs’ mouth was pried open, and his teeth were compared not only with the tooth marks on several injured victims present, but also with others in the courtroom.

Judges readily accepted this presentation of bite mark evidence to substantiate the allegations and at the conclusion of the trial, Reverend Burroughs was convicted of witchcraft by the Court of Oyer and Terminer and was hanged on August 19, 1692.

The Cheese Thief

The first bite mark case to be reported as an American judicial opinion was the 1954 Texas case of Doyle v. State.(4) This particular case involved a bite mark left in a piece of cheese which was found at the scene of a break and enter at a grocery store. The investigating sheriff of the case approached the suspect, who happened to be in custody for an unrelated offence, requesting he voluntarily bite into a piece of cheese. The suspect complied and later a firearms examiner photographed and made plaster casts of both cheeses. The firearms examiner and a dentist then analysed both exhibits. The suspect was convicted as a result of the damning testimony of these two experts who believed that both pieces of cheese had been bitten by the same set of teeth.

The Wayne Boden murders

The Canadian judicial system was presented with its first bite mark case in 1972 in the Alberta Supreme Court. More commonly referred to in the tabloid press as ‘The Vampire Rapist’, this case was the first in which bite marks in human skin were used to identify the perpetrator of a bite.(5) Also noteworthy is the fact that this particular case was the first in which bite mark evidence from multiple cases could be linked to a single offender.

Wayne Boden sexually assaulted and murdered four young women over a 16 month period, including one in a city some distance away from the other victims. His ‘calling card’ or ‘trademark’ was to leave bite marks on his victims, particularly to their breasts. Two days following the discovery of the last victim’s body, Boden was apprehended as a possible suspect. This last victim, a 33-year-old high school teacher named Elizabeth Porteous, had suffered bite marks to one of her breasts and her neck.

The police enlisted the services of a local orthodontist, Gordon Swann, in an effort to prove that the marks on Porteous' breasts and neck were Boden's bite marks. At the time there was nothing in the Canadian forensic literature on bite mark evidence. The orthodontist then wrote to the FBI seeking their assistance. In response the FBI referred him to an expert in England.

Armed with this knowledge the orthodontist then conducted a detailed examination of these injuries in conjunction with models and wax impressions of Boden’s dentition. His analysis indicated 29 points of similarity between the injuries on the victim and the suspect’s dentition thus providing enough basis with which to positively conclude that the bite marks were inflicted by the accused.

The details of the link established between Boden and the latest victim sparked investigators from other law enforcement agencies to review the previous three unsolved cases that exhibited overlapping traits. The forensic odontologist from the fourth case was asked to perform an analysis on the bite marks on one of these earlier victims.

The bite marks from both cases exhibited similarities and as a result police interviewed Boden about the three unsolved homicides. Boden provided detailed confessions to all three and was sentenced to life imprisonment. He died in custody in 2006, from skin cancer.

Increasing Understanding of the Forensic Value of Bite Marks, Victim and Biter Demographics and Types of Crime

The number of bite mark cases reported globally prior to the 1950s is limited in comparison to the more recent experience. During this early era, the predominance of reported cases came from Europe and Japan, however, the number of reported bite mark cases surged in the 1970s with many of these from the United States.

During the years preceding the formal recognition of bite mark analysis as a branch of forensic odontology, appreciation of the potential value of bite mark evidence by personnel extending from the crime scene to the autopsy room was slow. Once high-profile criminal cases, such as Ted Bundy, demonstrated the evidentiary importance of bite marks, law enforcement personnel, coroners, pathologists and dentists were educated to carefully document bite marks for subsequent analysis.

Anatomic Location

In 1983 a study was conducted to focus primarily on discerning the anatomical locations of the bite marks, the sex and age of victims sustaining these injuries, and the types of crime in which these injuries featured.(7) The main aim for this type of research was to provide prior knowledge of where these injuries were most likely to be found in order to assist with their initial detection. Similar studies have been conducted(8, 9) since this time to update and augment previous findings. However, common to each study were the following observations:

  1. Bite marks are found on almost all areas of the body.
  2. It is common to find more than one bite mark on a victim, often in different anatomical locations.
  3. Bite marks occurred primarily in sex-related crimes, child abuse cases and cases involving physical altercations of various types.
  4. Female victims are most commonly bitten on the breasts, arms and legs in descending order of frequency and males most frequently on the arms, back and hands.
  5. Patterns of distribution of bite marks are discernable and variable and are based in part by the type of crime involved, the age and sex of the victim, whether the bite mark is on the victim or the attacker and the sex and age of the perpetrator.

Anatomy of the typical human bite mark on skin

Adult human dentition consists of 32 teeth, each of which varies in terms of its size, shape and function. The full complement of teeth comprises two incisors, one canine, two premolars and three molars in each upper and lower quadrant.

The characteristic oval-patterned injury that results from the action of biting will typically only reveal several of the anterior teeth in each arch, namely the canines and the incisors.

A very frequent observation noted during bite mark investigations is that the mandibular (lower) anterior teeth are exhibited more clearly than the maxillary (upper) teeth. While numerous schools of thought exist as to the reason governing such as a phenomenon, the most common proposal is that the mandibular jaw is capable of movement during bite infliction whilst the maxillary is not.

References

(1) American Society of Forensic Odontology. (2007) Introduction to forensic odontology. In Manual of Forensic Odontology. (Herschaft, Alder, Ord, Rawson & Smith ed.), 4th edn rev., pp. 1-6, Impress Printing & Graphics, New York.

(2) Wagner, G. N. (1997). Scientific Methods of Identification. In Forensic Dentistry. (P. G. Stimson and, C. A. Mertz ed.), pp. 1-36, CRC Press, New York.

(3) American Society of Forensic Odontology. (2009). American Board of Forensic Odontology Diplomates Reference Manual. Section 3: Policies, Procedures, Guidelines & Standards.

(4) Doyle v. State, 159 Tex. C.R. 310, 263 S.W.2d 779.

(5) Swann, G. (1974). The Wayne Boden Murders. International Journal of Forensic Dentistry, 2(4), 32-42.

(7) Vale, G. L. and Noguchi, T.T. (1983). Anatomical distribution of human bite marks in a series of 67 cases. Journal of Forensic Sciences, 28, 619-621.

(8) Pretty, I. A. and Sweet, D. (2000). Anatomical location of bite marks and associated findings in 101 cases from the United States. Journal of Forensic Sciences, 45, 812-814.

(9) Freeman, A. J., Senn, D. R. and Arendt, D.M. (2005). Seven Hundred Seventy Eight Bite Mark: Analysis by Anatomic Location, Victim, and Biter Demographics, Type of Crime, and Legal Disposition. Journal of Forensic Sciences, 50, 1436-1443.

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